Reaction synthesis of MoSi{sub 2}-Al{sub 2}O{sub 3} composite using MoO{sub 3}, Al and Si powders

Book · Sun Oct 01 04:00:00 EDT 1995

OSTI ID:100541

Deevi, S C ^[1]; Deevi, S ^[2]

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1. Philip Morris, USA, Richmond, VA (United States)
2. CeraMat Technologies, Oak Ridge, TN (United States)

In-situ synthesis of a composite of MoSi{sub 2}-Al{sub 2}O{sub 3} was carried out by reacting a thermite mixture consisting of MoO{sub 3}, Al, and Si powders. The reaction was found to be extremely fast and violent, and a diluent was required to moderate the reaction. Thermal behavior of the thermite mixture was studied using DTA at different heating rates, and DTA was interrupted at different temperatures to determine the reaction mechanism. X-ray characterization of the products obtained at different temperatures reveals that the mechanism consists of a reduction of MoO{sub 3} by Al to MoO{sub 2} followed by a simultaneous oxidation of Al to Al{sub 2}O{sub 3} and synthesis reaction between reduced Mo and Si to form MoSi{sub 2}. The rate determining step is found to be reduction of MoO{sub 2} by Al and oxidation of Al to Al{sub 2}O{sub 3}. The thermite reaction was moderated by adding Mo and Si to the mixture of MoO{sub 3}, Al, and Si such that the ratio of MoSi{sub 2} to the thermite was in the range of 60:40 to 90:10.

• OSTI ID: 100541
• Report Number(s): CONF-941144--; ISBN 1-55899-266-9
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
ALUMINIUM OXIDES
CHEMICAL REACTIONS
COMPOSITE MATERIALS
DIFFERENTIAL THERMAL ANALYSIS
EXPERIMENTAL DATA
MICROSTRUCTURE
MOLYBDENUM OXIDES
MOLYBDENUM SILICIDES
REDOX PROCESS
SILICON
SYNTHESIS
THERMITE PROCESS
X-RAY DIFFRACTION